Our experimental results demonstrated that when optical trapping was applied to late-moving metaphase chromosomes, the trapped chromosomes initiated movement to the metaphase with the velocities two to eight times the normal rate depending on the chromosome size, geometry, and trapping site. At the initiation of anaphase, a pair of chromatids could be held by the optical trap and kept motionless throughout anaphase while the other pairs of chromatids separated and move to opposite spindle poles. A pulsed-laser microbeam (optical scissors) and laser-based trap (optical tweezers) have been successively combined to dissect and manipulate chromosome in PTK2 and newt lung epithelial cells. Our experiments demonstrate that the laser-based optical force trap is a potential new technique to study noninvasively the mitotic spindle , of living spindle, of living cells, and cell genetics.